Electromagnetic control device



Dec. 21, 1948. 0, c, WALLEY 2,457,017

ELECTROMAGNETIC CONTROL DEVICE Filed Oct. 8, 1945 2 Sheets-Sheet 1 4 a Fig.1. 3 l-.

. I Omar-C. Walla],

WITNESSES: INVENTOR TM a m Mafi ATTORNEY Dec. 21, 1948. o. c. WALLEY 2,457,017

ELECTROMAGNETIC CONTROL DEVICE Filed Oct. 8, 1945 2 Sheets-Sheet 2 WITNESSES: INVENTOR I OmarCh/alley.

BY 61...)- W. ATTORNEY Patented Dec. 21, 1948 ELECTROMAGNETIC CONTROL DEVICE Omar C. Walley, Lima, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 8, 1945, Serial No. 621,078

Claims. 1 My invention relates to contactors and other electromagnetic control devices and aims at devising apparatus which accomplish the appointed control or switching performance with a design of especially small compass and light weight as compared with devices heretofore available for similar purposes.

The contactors used on aircraft, for instance, must be capable of remaining in the proper control or contact position under acceleration and shock conditions which impose on the movable armature a force many times the force of gravity. Such contactors are further supposed to operate properly under inconstant voltage conditions and hence should pick up under voltages reduced to, for instance, 50% of the rated value, and they are also supposed to require a hold-in voltage of even smaller percentage, for instance, down to 20% of the rated voltage.

It, therefore, is .an object of my invention to provide an electromagneticcontactor or the like control device whose electromagnetic system has an increased efiiciency so as to comply with requirements of the above-exemplified type without necessitating the use of an undesirably large magnet structure or coil.

Another object, allied to the foregoing, is the provision of an electromagnetic device of extremely light weight and small dimensions whose armature, nevertheless, is strongly spring-biased toward the open position and strongly held in the closed position when picked up so as to withstand shock forces while being controllable by a low pick-up voltage and an extremely low holding voltage- In order to achieve these objects, and in accordance with one of the features of my invention, I provide a U-shaped magnetic frame structure with a central core, arrange the appertaining spring-biased armature in front of the respective pole faces of frame structure and core, and equip the frame structure with a magnetizable extension which is so located as to include the armature in a pickup flux path when the armature is in open, i. e., dropped-oil position.

These and other features of my invention will be apparent from the drawing, in which:

Figure 1 represents an axial section through a contactor accordin to the invention; Fig. 2 is a front view (seen from below of Fig. 1), and Fig. 3 a side view of the same contactor (seen from the left of Fig. 1); and Fig. 4 is a diagram of the appertaining circuit connections.

According to the drawing, the contactor has a substantially U-shaped magnetic frame structure i which has outwardly extending flanges 2. A magnetic core 3 is firmly attached to the bottom of the frame structure I by means of a screwv 4. Hence, the field structure as a whole is of the three-legged type. The core 3 carries a spool 5 with a pick-up coil 6 and a. high-resistance holding coil 1. A face plate 8 of magnetizable material is mounted on flanges 2- and, has a circular opening so as to form together with core 3 an interstice 9. The pole faces I 0 and H of core 3 and face plate 8 lie in a common geometrical plane. Mounted on the face plate 8 is a spacer [2 consisting also of magnetizable material. Another magnetizable plate l3, also with a circular opening, is attached to the spacer 12 so as to form together therewith a magnetic membcr which may be considered to represent an extension of the frame structure I.

A guide pin l4 extends coaxially to the core 3 and is firmly secured thereto. A sleeve member I5 is slidably seated on the guide pin I4 and is normally biased by a kick-out spring 5 in the direction away from the core. A disc-shaped magnet armature I1 is loosely mounted on the sleeve member IS. The plate l3 has a circular opening which, in the illustrated open position of the armature ll, forms a gap I8.

A base plate I9 is mounted on the plate l3, and all parts 2, 8, l2, l3 and i9 are firmly secured together by means of screws 20 which may be threaded into corresponding threaded bores of the flange 2.

i9 and engages the recessed end of an arm 22 which is brazed to the shoulder of the sleeve member l5 and carries an insulation button 23. Two contact springs 24 and are attached to the base plate !9. In the illustrated position of arm 22, the contact spring 24 rests resiliently against contact spring 25 so that a circuit connection is established between springs 24 and 2'5 or the terminals and wires attached thereto. When arm 22 moves upwardly with reference to the showing in Fig. 1, button 23 engages the contact spring 24 and moves it out or contact with spring 25. Contact springs 24 and 25 form an auxiliary contact device for controlling the excitation of the holding coil 1 as will be explained below in conjunction with Fig. 4.

The main contact device of the relay comprises a movable contact bar 26 which carries two contacts 21 and 28 for engagement with two respective stationary contact pieces 29 and 30 (Fig. 3) that are mounted on the base plate l9 and provided with terminals for connection to the circuit to be controlled. The contact pieces 26 and 30 have respective extensions 26' and 30' abutting against the base plate I! (Fig. 3). The contact bar 26 is displaceably mounted on sleeve IS. A cup-shaped member ii is arranged on the sleeve member i5 and serves as an abutment for a helical contact spring 32. Spring 32 tends to hold the contact bar 26 against the adjacent arm 22 and is compressed when the armature l1 and the associated sleeve and contact assembly are moved toward the magnetic core. in order to secure the necessary contact pressure between movable contacts 21, 26 and stationary contacts 28, 30.

When the armature and contact assembly are in the illustrated dropped-off or open position, the armature ll lies in a magnetic flux path which extends through the frame structure I, the members 6, l2 and I3, the gap it, the armature l1, and the air gap between the armature I1 and the pole face I!) of core 3. When the structure is magnetized by electric energization of coil 6, the magnetic flux acts to move the armature ll toward thepole face ill in opposition to the biasing force of the spring 16. When the armature I 1 reaches the closed position it seals against pole faces l and II and bridges the interstice 9 so that a magnetic holding circuit is closed from the core 3 through the armature and the face plate 6.

Due to the existence of an auxiliary flux path in the open position of the armature and by virtue of the above-described design of the device, a magnetizing force of relatively low magnitude is sufficient to overcome the strong force of the spring l6 and to move the armature against the core. Thereafter, a much smaller magnitude of magnetic force suffices to maintain the device in closed condition. In accordance therewith, the relay control circuit is so connected with the two coils that the high-resistance holding coil 1 lies in series with the low-resistance pick-up coil but is shorted by the contact springs 24 and 25 when the relay is in dropped off condition. Hence, only coil 6 is at first effective to actuate the relay. When coil 6 is energized, the armature I1 is attracted toward the pole faces l0 and II and moves the contact bar 26 toward the stationary contacts 29 and 3|] until these contacts are engaged by the bar contacts 21 and 28. From then on, the bar 26 is stepped while the armature I1 and the sleeve with arm 22 are permitted to travel a further extent under increasing compression of the contact pressure spring 32. During the period of this overtravel motion, and shortly before the armature ll seals against the pole faces I0 and II, the engagement of contacts 24 and 26 is interrupted. This interruption eliminates the short circuit of the holding coil 1 so that the latter becomes energized in series with the pick-up coil 6. Hence, a reduced current is thereafter eflective to hold therelay closed.

This performance will be more fully understood from the circuit diagram of Fig. 4 in which the main contact device of the relay is schematically represented at M and the auxiliary contact device at A. The load circuit to be controlled by contact device M is denoted by L, while C indicates the control circuit for energizing the relay coils 6 and 1. When a switch or contact S in the control circuit is closed, the pick-up coil 6 is energized and causes the relay to first close contact device M and then open the contact device A. Thereafter, both coils 6 and 1 are excited in series connection until contact S is opened.

It will be recognized from Figs. 1 to 3 that contactors of the type described are of a simple construction which is suitable for mass production and affords a high pick-up force and a high holding force while requiring relatively low energy for its operation. The contactors are also characterized by light weight and are capable of fast action due to the light weight and the high magnetic forces. In order to illustrate these advantages, it may be mentioned that contactors designed according to the drawing and having a width of the frame portion of slightly less than three inches, all other dimensions being substantially proportionate, were able to withstand shocks of approximately fifteen times gravity without changing their contact position and picked up on 50% rated voltage while requiring 20% rated voltage for maintaining the armature and contact assembly in the closed position. These relays permitted producing a contact force of approximately four pounds per contact and were lighter in weight than any other electromagnetic device suitable for similar purposes and capable of achieving comparable advantages.

It will be understood by those skilled in the art that devices according to my invention can be modified as regards the arrangement and detail design of its component parts without departing from the principle and gist of the invention and within the essential features of the invention as set forth in the claims annexed hereto.

I claim as my invention:

1. An electromagnetic control device, comprising a field structure having a centrally located core and magnetizing coil means disposed on said core, said structure having magnetic pole faces of different magnetic polarity, an armature movable between a closed position in which it bridges said pole faces and an open position axially away from said pole faces, spring means for biasing said armature toward said open position, and magnetic means forming an extension of said frame structure which projects beyond said pole faces toward said armature when the latter is in said open position so as to include said armature in a magnetic pick-up circuit extending through said frame structure, said extension and said armature in said open position of the latter, said magnetic means having a portion extending substantially in the plane of said armature in its open position and another portion extending substantially in the plane of said armature in its closed position.

2. An electromagnetic control device, comprising a substantially U-shaped magnet frame structure, a centrally disposed magnet core attached to the bottom of said structure, magnetizing coil means disposed on said core, said structure and said core having respective pole faces located substantially in a common geometrical plane, an armature movable between a closed position in which it bridges said pole faces and an open position axially away from said pole faces, spring means for biasing said armature toward said open position, and magnetic means mounted on said frame structure at the side of said armature and having a circular opening, said magnetic means having one portion forming together with said armature a gap which surrounds said armature and extending substantially in the plane thereof when said armature is in said open position, said magnetic means having another portion extending substantially in the plane of said armature in its closed postion.

3. An electromagnetic control device, comprising a substantially U-shaped magnet frame structure having two outwardly extending flanges, a magnet core centrally disposed in said structure and attached to the bottom thereof, magnetizing coil means disposed on said core, a magnetic face plate mounted on said flanges and extending inwardly toward said core, said plate and said core having pole faces located substantially in a common plane, an armature movable between a closed position in which it bridges said pole faces and an open position axially away from said pole faces, spring means for biasing said armature toward said open position, and magnetic means mounted on said face plate and forming together with said armature a gap which surrounds said armature in said open position.

4. An electromagnetic device, comprising a three-legged magnetizable field structure having a pole face at the end of each leg, magnetizing coil means disposed on the center leg of said structure, a guide pin mounted on said center leg and extending coaxially away therefrom, a movable assembly slidably disposed on said guide pin and having a disc-shaped magnet armature, said assembly being movable between a closed position in which said armature bridges said pole faces so as to complete a magnetic holding circuit and an open position in whichsaid armature lies axially away from said pole faces, spring means for biasing said assembly toward said open position, and magnetic means mounted on the two outer legs of said structure at the side of said armature and forming together with said armature a magnetic pick-up circuit when said tion and another portion extending substantially in the plane of said armature in its closed position.

5. An electromagnetic device, comprising a three-legged field structure, the two outer legs of said structure having outwardly extending flanges, respectively, a magnetic face plate mounted on said flanges and extending inwardly toward the center leg of said structure, said plate and said core having pole faces located substantially in a common plane, a guide pin mounted on said core and extending coaxially away therefrom, a movable assembly slidably disposed on said guide pin and having a disc-shaped magnet armature, said assembly being movable between a closed position in which said armature bridges said pole faces and an open position in which said armature lies axially away from said pole faces, spring means for biasing said assembly toward said open position, magnetic means having a circular opening and being mounted on said structure at the side of said armature so 7 as to include said armature in a magnetic pick- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 766,391 Sargent et al. Aug. 2, 1904 1,700,314 Hartwig Jan. 29, 1929 2,332,139 Finnegan Oct. 19, 1943 2,339,610 Baker Jan. 18, 1944 2,372,853 Ray Apr. 3, 1945 

